Fiber optic telecommunication networks use optical signals to transmit data and voice information. The data and voice information is typically generated in a transmitter, transmitted over an optical fiber network, switched in cross-connects and routers and finally converted back into an electrical signal in a receiver. During transmission of an optical signal, an optical filter may be used at several stages. For example, an optical filter may be used in a transmitter to provide signal format conversion. In a transparent network, optical filters might be necessary to regenerate the signal during transmission or to perform all-optical wavelength conversion to avoid wavelength blocking. Finally, optical filters might be needed to compensate for dispersion.
Prior art devices such as pulse shapers have been proposed for modifying the temporal characteristic of a pulse sequence by first spectrally broadening the signal and introducing amplitude and phase masks across the continuous spectrum of the signal using a photorefractive or holographic lens, before recombining the pulses. Such devices are, however, limited in their ability to provide signal processing on individual spectral components of an optical signal
It would be desirable, therefore, to have a method and apparatus which provides for flexible and individual processing of discrete spectral components of an optical signal to provide real time delays between discrete spectral components and/or to allow signal format conversion, signal regeneration, wavelength conversion and/or dispersion compensation.